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4 Mar 2017 : A tale of woe: failing to heed the certificate-pinning warnings #
As I mentioned previously, last month I discovered rather abruptly that Firefox revoked the StartCom root certificate used to sign the TLS certificate on my site. Ouch. To ease the pain, I planned to move over to using Let's Encrypt, a free service that will automatically generate a new certificate for my site every few months. Both StartCom and Let's Encrypt use a similar technique: they verify only that I have control over the apache2 user on my server by demonstrating that I can control the contents of the site. But the pain hurt particularly badly because I'd been using certificate-pinning, which essentially prevents me using any other certificates apart from a small selection that I keep as backups. Let's Encrypt doesn't give you control over the certificates it signs. The result: anyone who visited my site in the last month (of which there are no-doubt countless millions) would be locked out of it. It's the certificate-pinning nightmare everyone warns you about. So I ratcheted the pinning down from a month to 60 seconds and waited for browsers across the world to forget my previously-pinned certificate.
Today, the 30 days finally expired. In theory, my previously pinned certificates are no longer in force and it's safe for me to switch over to Let's Encrypt. And so this is what I've done.
Check for yourself by visiting www.flypig.org.uk and hitting the little green padlock that appears in the address bar. Depending on the browser it should state that it's a secure connection, verified by Let' Encrypt.
Does the stark black-and-white page render beautifully? Then great! Does it say the certificate has expired, is invalid, or has been revoked? Well, then I guess I screwed up, so please let me know.
I didn't really learn my lesson though. In my desparate need to get a good score on securityheaders.io, I've turned certificate-pinnng back on (thanks Henrik Lilleengen for leading me astray). Nothing could possibly go wrong this time, right?

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